With the victory, the Fighting Irish notched a perfect 12-0 season for the first time since 1988, when Coach Lou Holtz guided the team to their last national championship.
Notre Dame will play the winner of next week's SEC championship game between No. 2 Alabama and No. 3 Georgia in the Jan. 7 BCS national championship game at Miami.
Clinging to an eight-point lead late the fourth quarter, the Irish defense stopped the Trojans four times on a goal-line stand as USC quarterback Max Wittek misfired on a fourth-and-goal pass to Soma Vainuku.
Everett Golson completed 15-of-26 passes for 217 yards and Theo Riddick racked up 146 yards with a TD on 20 carries for Notre Dame.
Wittek -- subbing for injured starter Matt Barkley -- completed 14-of-23 passes for 186 yards, one score and two interceptions for the Trojans (7-5).